Polygon PoS Development

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name: polygon-pos-dev description: Comprehensive guide for Polygon PoS blockchain development. Use when deploying smart contracts to Polygon, testing on Amoy testnet, getting test tokens from faucets, or verifying contracts on Polygonscan. Supports Foundry framework with deployment scripts and testing strategies.

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Polygon PoS Development

End-to-end guide for developing and deploying smart contracts on Polygon PoS blockchain using Foundry.

Overview

Polygon PoS is an EVM-compatible Proof-of-Stake sidechain for Ethereum with:

Low transaction costs (fraction of a cent)

Fast block times (~2 seconds)

High throughput (65,000+ TPS theoretical)

Full Ethereum tooling compatibility

POL token for gas fees

Default Network: Amoy Testnet (Chain ID: 80002) - Use for all testing before mainnet.

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🚀 Quick Navigation

For Agents/Fast Deployment: Jump to Quick Start Path (5-10 min)

For Production/Thorough Testing: Jump to Complete Development Path (30-60 min)

For Reference: See sections below for Network Configuration, Faucets, Troubleshooting

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Two Development Paths

Choose based on your needs:

| Aspect | Quick Start Path | Complete Development Path | |--------|------------------|---------------------------| | Time | 5-10 minutes | 30-60 minutes | | Best for | Prototypes, demos, simple contracts | Production, complex systems, mainnet | | Testing | Basic compilation check | Unit tests, integration tests, fork tests | | Scripts Used | None (direct forge commands) | Direct forge commands with all options | | Documentation | Minimal | Full reference guides | | Verification | Automatic during deploy | Multiple methods with troubleshooting | | Agent-Friendly | ✅ Optimized for speed | ⚠️ Comprehensive but slower |

Path 1: Quick Start (Minimal Time - Agent-Friendly)

Best for: Fast deployment, simple contracts, prototyping Time: 5-10 minutes What you get: Contract deployed and verified on testnet

Skip to Quick Start Path below.

Path 2: Complete Guide (Full Development Workflow)

Best for: Production contracts, complex systems, thorough testing Time: 30-60 minutes What you get: Fully tested, optimized, and production-ready deployment

Skip to Complete Development Path below.

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Quick Start Path

Goal: Deploy a contract to Polygon Amoy testnet in minimal steps.

Prerequisites

Foundry installed: curl -L https://foundry.paradigm.xyz | bash && foundryup

Wallet with private key

Polygonscan API key (get from https://polygonscan.com/myapikey)

Step 1: Create Project (30 seconds)

forge init my-polygon-project
cd my-polygon-project

Step 2: Configure Environment (1 minute)

Create .env file:

PRIVATE_KEY=your_private_key_without_0x_prefix

Step 3: Get Testnet Tokens (2 minutes)

Visit: https://www.alchemy.com/faucets/polygon-amoy

Paste your wallet address

Claim 0.2-0.5 POL (no signup needed)

Step 4: Deploy (1 minute)

# Deploy to Amoy testnet
forge script script/Counter.s.sol:CounterScript \
    --rpc-url https://rpc-amoy.polygon.technology \
    --private-key $PRIVATE_KEY \
    --broadcast

Done! Your contract is deployed and verified on Amoy testnet.

View at: https://amoy.polygonscan.com/address/YOUR_CONTRACT_ADDRESS

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Complete Development Path

Goal: Production-ready deployment with comprehensive testing and optimization.

Phase 1: Setup (5 minutes)

1. Install Foundry:

curl -L https://foundry.paradigm.xyz | bash
foundryup

2. Initialize Project:

forge init my-polygon-project
cd my-polygon-project

3. Configure for Polygon:

Update foundry.toml with Polygon settings:

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
solc_version = "0.8.24"
optimizer = true
optimizer_runs = 200
[rpc_endpoints]
amoy = "https://rpc-amoy.polygon.technology"
polygon = "https://polygon-rpc.com"
[etherscan]
amoy = { key = "${POLYGONSCAN_API_KEY}", url = "https://api-amoy.polygonscan.com/api" }
polygon = { key = "${POLYGONSCAN_API_KEY}", url = "https://api.polygonscan.com/api" }

4. Setup Environment:

Create .env file:

PRIVATE_KEY=your_private_key
WALLET_ADDRESS=0xYourAddress
POLYGONSCAN_API_KEY=your_api_key

Phase 2: Write & Test Contracts (10-20 minutes)

1. Write Contract (or use assets/sample-contracts/HelloWorld.sol as template)

2. Write Tests:

// test/MyContract.t.sol
import "forge-std/Test.sol";
import "../src/MyContract.sol";
contract MyContractTest is Test {
    MyContract public myContract;
    
    function setUp() public {
        myContract = new MyContract();
    }
    
    function testDeployment() public {
        assertEq(myContract.owner(), address(this));
    }
}

3. Run Tests:

forge test -vvv                    # Run tests
forge test --gas-report            # Check gas usage
forge coverage                     # Check coverage

4. Fork Testing (optional):

# Test against real Polygon state
forge test --fork-url https://polygon-rpc.com

See references/testing-strategies.md for comprehensive testing patterns.

Phase 3: Get Testnet Tokens (2-5 minutes)

Visit one of these faucets:

Alchemy (recommended - no auth): https://www.alchemy.com/faucets/polygon-amoy QuickNode: https://faucet.quicknode.com/polygon/amoy GetBlock: https://getblock.io/faucet/matic-amoy/ Chainlink: https://faucets.chain.link/polygon-amoy LearnWeb3: https://learnweb3.io/faucets/polygon_amoy/

Phase 4: Deploy to Testnet (2-5 minutes)

forge script script/Deploy.s.sol \
    --rpc-url amoy \
    --private-key $PRIVATE_KEY \
    --broadcast \
    --verify \
    --etherscan-api-key $POLYGONSCAN_API_KEY

Create a deployment script in script/Deploy.s.sol:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
import "forge-std/Script.sol";
import "../src/YourContract.sol";
contract DeployScript is Script {
    function run() external {
        uint256 deployerPrivateKey = vm.envUint("PRIVATE_KEY");
        
        vm.startBroadcast(deployerPrivateKey);
        
        // Deploy your contract
        YourContract yourContract = new YourContract();
        
        vm.stopBroadcast();
        
        console.log("Contract deployed to:", address(yourContract));
    }
}

See references/foundry-deployment.md for advanced deployment patterns.

Phase 5: Verify Contract (1-2 minutes)

If not verified during deployment:

forge verify-contract \
    CONTRACT_ADDRESS \
    src/MyContract.sol:MyContract \
    --chain-id 80002 \
    --etherscan-api-key $POLYGONSCAN_API_KEY

See references/contract-verification.md for troubleshooting verification issues.

Phase 6: Test on Testnet (5-10 minutes)

1. View on Explorer: https://amoy.polygonscan.com/address/CONTRACT_ADDRESS 2. Interact with Contract: Use cast or web interface 3. Test All Functions: Verify behavior matches expectations 4. Monitor Gas Costs: Check if optimization needed

Phase 7: Deploy to Mainnet (5 minutes)

⚠️ IMPORTANT: Complete mainnet deployment checklist first!

See Mainnet Deployment Checklist below.

forge script script/Deploy.s.sol \
    --rpc-url polygon \
    --private-key $PRIVATE_KEY \
    --broadcast \
    --verify \
    --etherscan-api-key $POLYGONSCAN_API_KEY

End of Complete Development Path ✅

Network Configuration

Amoy Testnet (Recommended for Testing)

| Property | Value | |----------|-------| | Network Name | Polygon Amoy | | Chain ID | 80002 | | Currency | POL | | RPC URL | https://rpc-amoy.polygon.technology | | WebSocket | wss://polygon-amoy.drpc.org | | Explorer | https://amoy.polygonscan.com | | Faucets | Multiple (see below) |

Polygon Mainnet

| Property | Value | |----------|-------| | Network Name | Polygon | | Chain ID | 137 | | Currency | POL | | RPC URL | https://polygon-rpc.com | | WebSocket | wss://polygon.drpc.org | | Explorer | https://polygonscan.com |

Getting Testnet Tokens

Multiple faucets available for Amoy testnet POL tokens.

Quick Access

Run the faucet helper script:

./scripts/get-testnet-tokens.sh

Available Faucets

Alchemy Faucet (Recommended - No auth required)

URL: https://www.alchemy.com/faucets/polygon-amoy

Amount: 0.5 POL/day (with account), 0.2 POL/day (without)

Requirements: None

QuickNode Faucet

URL: https://faucet.quicknode.com/polygon/amoy

Amount: 0.1 POL/day (2x with tweet)

Requirements: Connect wallet

GetBlock Faucet

URL: https://getblock.io/faucet/matic-amoy/

Amount: 0.1 POL/day

Requirements: Login

Chainlink Faucet

URL: https://faucets.chain.link/polygon-amoy

Amount: 0.1 POL/day

Requirements: GitHub auth

LearnWeb3 Faucet

URL: https://learnweb3.io/faucets/polygon_amoy/

Amount: 0.1 POL/day

Requirements: GitHub auth

Tips:

Most faucets limit to 1 request per 24 hours

If rate-limited, try a different faucet

Some offer bonus tokens for tweeting

Deployment Workflow

Environment Setup

Create .env file (see assets/sample-contracts/.env.example):

PRIVATE_KEY=your_private_key_here
WALLET_ADDRESS=0xYourAddress
POLYGONSCAN_API_KEY=your_api_key_here

Add to .gitignore:

.env
broadcast/
deployments/

Deploy to Testnet

Option 1: Use helper script (recommended)

./scripts/deploy-foundry.sh

Option 2: Manual deployment

forge script script/Deploy.s.sol \
    --rpc-url amoy \
    --private-key $PRIVATE_KEY \
    --broadcast \
    --verify

Option 3: Deploy without verification

forge script script/Deploy.s.sol \
    --rpc-url amoy \
    --private-key $PRIVATE_KEY \
    --broadcast

Deploy to Mainnet

⚠️ IMPORTANT: Test thoroughly on Amoy first!

# Use deployment script and select mainnet option
./scripts/deploy-foundry.sh

For detailed deployment patterns, see references/foundry-deployment.md.

Testing Strategies

Local Testing

Write tests in test/ directory:

// test/MyContract.t.sol
import "forge-std/Test.sol";
import "../src/MyContract.sol";
contract MyContractTest is Test {
    MyContract public myContract;
    
    function setUp() public {
        myContract = new MyContract();
    }
    
    function testFunction() public {
        // Test logic
    }
}

Run tests:

forge test              # Run all tests
forge test -vvv         # Verbose output
forge test --gas-report # Show gas usage

Fork Testing

Test against real Polygon state:

forge test --fork-url https://polygon-rpc.com

Testnet Testing

Deploy to Amoy and test with real transactions. See references/testing-strategies.md for comprehensive testing patterns.

Contract Verification

Verification makes your contract code public and trustworthy.

During Deployment (Recommended)

forge script script/Deploy.s.sol \
    --rpc-url amoy \
    --private-key $PRIVATE_KEY \
    --broadcast \
    --verify \
    --etherscan-api-key $POLYGONSCAN_API_KEY

After Deployment

Option 1: Use helper script

./scripts/verify-contract.sh

Option 2: Manual verification

forge verify-contract \
    CONTRACT_ADDRESS \
    src/MyContract.sol:MyContract \
    --chain-id 80002 \
    --etherscan-api-key $POLYGONSCAN_API_KEY \
    --verifier-url https://api-amoy.polygonscan.com/api

With Constructor Arguments

forge verify-contract \
    CONTRACT_ADDRESS \
    src/MyContract.sol:MyContract \
    --chain-id 80002 \
    --etherscan-api-key $POLYGONSCAN_API_KEY \
    --constructor-args $(cast abi-encode "constructor(address,uint256)" 0x123... 1000)

For troubleshooting verification issues, see references/contract-verification.md.

Common Workflows

Which Path Should I Use?

Use Quick Start Path when:

You need fast deployment (prototyping, demos)

Contract is simple and low-risk

You're an AI agent with limited time

Testing is minimal or done elsewhere

Use Complete Development Path when:

Deploying to mainnet

Contract handles real value

Complex logic requiring thorough testing

Team collaboration and code review needed

Security is critical

Mainnet Deployment Checklist

Before deploying to mainnet:

[ ] All tests passing (forge test)

[ ] Deployed and tested on Amoy testnet

[ ] Contract verified on Amoy

[ ] Security review completed

[ ] Gas optimization done

[ ] Documentation complete

[ ] Constructor arguments double-checked

[ ] Sufficient POL in wallet for gas

[ ] Deployment script tested

[ ] Team notified of deployment

Sample Contract Pattern

Example smart contract structure for Polygon:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;
contract HelloWorld {
    address public owner;
    string public message;
    uint256 public updateCount;
    
    event MessageUpdated(address indexed updater, string newMessage);
    
    error NotOwner();
    error EmptyMessage();
    
    constructor(string memory initialMessage) {
        owner = msg.sender;
        message = initialMessage;
    }
    
    modifier onlyOwner() {
        if (msg.sender != owner) revert NotOwner();
        _;
    }
    
    function setMessage(string calldata newMessage) external {
        if (bytes(newMessage).length == 0) revert EmptyMessage();
        message = newMessage;
        updateCount++;
        emit MessageUpdated(msg.sender, newMessage);
    }
}

Key patterns:

Use custom errors instead of require strings (gas-efficient)

Emit events for important state changes

Use modifiers for access control

Optimize for Polygon's low gas costs

Safety Rules

1. Test First: Always test on Amoy before mainnet 2. Never Commit Keys: Add .env to .gitignore 3. Verify Contracts: Always verify for transparency 4. Check Network: Double-check chain ID before deployment 5. Sufficient Balance: Ensure enough POL for gas 6. Save Addresses: Document deployed contract addresses 7. Audit Code: Security review before mainnet 8. Use Scripts: Automate deployments to reduce errors 9. Backup Keys: Securely backup private keys 10. Test Verification: Verify contracts on testnet first

Troubleshooting

Insufficient Funds for Gas

Error: insufficient funds for gas * price + value

Solution: Get testnet POL from faucets (run ./scripts/get-testnet-tokens.sh)

Contract Not Found

Error: src/MyContract.sol:MyContract not found

Solution: Check file path and contract name match exactly

RPC Connection Issues

Error: failed to get chain id

Solution:

Check internet connection

Try alternative RPC URL

Use dedicated RPC provider (Alchemy, QuickNode)

Verification Failed

Error: bytecode does not match

Solution:

Wait 1-2 minutes for contract to be indexed

Check constructor arguments are correct

Verify compiler settings match deployment

Gas Estimation Failed

Error: gas estimation failed

Solution:

Check contract logic for reverts

Ensure sufficient balance

Check function parameters

Resources

Foundry Documentation

Book: https://book.getfoundry.sh/

GitHub: https://github.com/foundry-rs/foundry

Polygon Documentation

Docs: https://docs.polygon.technology/

Gas Station: https://gasstation.polygon.technology/

Faucets: https://faucet.polygon.technology/

Block Explorers

Amoy: https://amoy.polygonscan.com

Mainnet: https://polygonscan.com

RPC Providers

Alchemy: https://www.alchemy.com/

QuickNode: https://www.quicknode.com/

Infura: https://infura.io/

Community

Discord: https://discord.com/invite/0xPolygonCommunity

Telegram: https://t.me/polygonhq

Reference Files

For detailed information:

references/foundry-deployment.md - Complete deployment guide

references/testing-strategies.md - Testing best practices

references/contract-verification.md - Verification troubleshooting

Scripts

Foundry installed: curl -L https://foundry.paradigm.xyz | bash && foundryup

Wallet with private key

Polygonscan API key (get from https://polygonscan.com/myapikey)

Step 1: Create Project (30 seconds)

forge init my-polygon-project
cd my-polygon-project

Step 2: Configure Environment (1 minute)

Create .env file:

PRIVATE_KEY=your_private_key_without_0x_prefix

Step 3: Get Testnet Tokens (2 minutes)

Visit: https://www.alchemy.com/faucets/polygon-amoy

Paste your wallet address

Claim 0.2-0.5 POL (no signup needed)

Step 4: Deploy (1 minute)

# Deploy to Amoy testnet
forge script script/Counter.s.sol:CounterScript \
    --rpc-url https://rpc-amoy.polygon.technology \
    --private-key $PRIVATE_KEY \
    --broadcast

Done! Your contract is deployed and verified on Amoy testnet.

View at: https://amoy.polygonscan.com/address/YOUR_CONTRACT_ADDRESS

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Insufficient Funds for Gas

Error: insufficient funds for gas * price + value

Solution: Get testnet POL from faucets (run ./scripts/get-testnet-tokens.sh)

Contract Not Found

Error: src/MyContract.sol:MyContract not found

Solution: Check file path and contract name match exactly

RPC Connection Issues

Error: failed to get chain id

Solution:

Check internet connection

Try alternative RPC URL

Use dedicated RPC provider (Alchemy, QuickNode)

Verification Failed

Error: bytecode does not match

Solution:

Wait 1-2 minutes for contract to be indexed

Check constructor arguments are correct

Verify compiler settings match deployment

Gas Estimation Failed

Error: gas estimation failed

Solution:

Check contract logic for reverts

Ensure sufficient balance

Check function parameters